Ah, but a thermal solar panel is more like 60% efficient, and it's built of glass, black spray paint and a garden hose. If the ultimate goal is to heat something with sunlight, you know which approach is the best. Several times as much area coated in special silicon stuff, or.... garden hose spray-painted black.
If the purposes are mixed, of course a photovoltaic panel can generate electricity for many purposes, while sunlight shining on a garden hose can only heat water. So it might be a more useful system, even more cost-effective, despite being much less thermally efficient.
It's the same with burning things to make heat, versus burning them for electricity and then using electric heaters.
If the purposes are mixed, of course a photovoltaic panel can generate electricity for many purposes, while sunlight shining on a garden hose can only heat water. So it might be a more useful system, even more cost-effective, despite being much less thermally efficient.
It's the same with burning things to make heat, versus burning them for electricity and then using electric heaters.